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Re: oil for caps (fwd)
---------- Forwarded message ----------
Date: Tue, 13 Jan 1998 09:59:37 -0600
From: David Huffman <huffman-at-FNAL.GOV>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: oil for caps (fwd)
I have updated some simulations of dielectric stress and Chip will add them
to his web site under my page. I have to agree that if the poly is thin and
irregular, which it usually is, then the capacitance will change
significantly with different dielectric constants.
Jim Monte's post about balancing the stress wrt breakdown of each dielectric
seem to be an excellent consideration. I cannot believe you can get more
capacitance without lowering the breakdown voltage.
"Captain, I can't change the laws of physics."
Dave Huffman
-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Monday, January 12, 1998 6:03 PM
Subject: Re: oil for caps (fwd)
---------- Forwarded message ----------
Date: Mon, 12 Jan 1998 16:58:51 -0500
From: Thomas McGahee <tom_mcgahee-at-sigmais-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Cc: Esondrmn-at-aol-dot-com
Subject: Re: oil for caps (fwd)
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: oil for caps (fwd)
> Date: Monday, January 12, 1998 1:48 PM
>
>
SNIP....
Ed & Ralph,
I have to agree with Ed here. The air with a constant of 1 is being
displaced by the SUNISO oil, and the increase is as we would expect
with just mineral oil. To lay the thing to rest once and for all
would be simple: perform the exact same experiment, but use mineral
oil this time. If the results are about the same, then that would show
that there is little or nothing to be gained by using oils of
higher dielectric constant.
HOWEVER, I believe that the looked-for increase probably WOULD show up
if the cap was made using 6 mil poly!!! The reason here is that the
thickness of the oil interface will now be much larger in proportion
to the poly thickness. Note that this would imply TWO things at least:
Higher dielectric constant oil COULD be used to increase the capacitance
of caps made using THIN poly, AND such use of high dielectric constant
oil WOULD put greater electric stress on the poly, because the
proportion of thickness would be quite different with thin poly.
Ralph, was your cap built using THIN poly? That would account for its
increase.
Hope this helps the discussion.
Fr. Tom McGahee